The Physics of Water Pumping

Roots very impressive post and the sort of stuff to get a better understanding

I would like to examine the difference between air and water pumping in more detail.

From a static point of view what you write in the quote extract above looks correct - ie the interaction of the penis expansion and the vacuum differs between air and water vacuums. However even in static pumping any reduction in vacuum caused by the penis expansion is nullified by continued pumping to maintain the desired vacuum so I am not sure the above tells the whole story.

However I suspect the differences you describe between water and air pumping related to compressability might be much more relevant in cyclic water pumping as you can achieve with the Mr Fantastic water pump. This type of pumping presumably causes pressure waves which would impact much more on the penis in the case of the water pump because of the incompressability of the media. What do you think?

Regards
Austfred

Excellent Roots, hopefully this will stop guys talking about partial vacuums pulling on the skin and the force not making it through to the tunica etc.
It’s only ever internal pressure that’s at work as you’d discover if you tried pumping your dick in outer space :D
Also the compression effect water has on the skin, you can feel it if you put your hand under water, it’s exactly why you get less bruising and edema from water pumping.
Great contribution.

I had a somewhat heated exchange with Sparkyx about this topic time ago. I standed for air pumping being better than water pumping exactly because air is compressible. Unfortunately I wasn’t able to make my point of view that clear.

What makes water pumping interesting at this point, is that you can target the bottom or top of your penis, unlikely than air pumping.

If you pump vertically, you should have more pull on th glans; if you pull upside down more force at the base. Where there is no water, there should be more expansion.

I had a somewhat heated exchange with Sparkyx about this topic time ago. I standed for air pumping being better than water pumping exactly because air is compressible. Unfortunately I wasn’t able to make my point of view that clear.

What makes water pumping interesting at this point, is that you can target the bottom or top of your penis, unlikely than air pumping.

How do you pull upside down?

Haha, he’s saying if the cylinder is perpendicular to the floor but the glans is facing the floor rather than the ceiling. Like if you are standing up and bending forward so your pelvis is pointed at the floor.

Pressure and pull is always at the tip of the cylinder.

Pressure is always equal throughout the cylinder. And pull isn’t a real thing. He is talking about if the cylinder is filled with water.

If it is filled with water, the weight of the water pushing down due to gravity will create more and more of a positive pressure gradient as you move from the ceiling side of the cylinder to the floor side, in the direction of gravity. Just like diving into the ocean, as you go deeper the pressure becomes greater. So this will create a technically slightly lower vacuum on the floor side of the cylinder as the weight of the water will be creating a positive pressure.

So if you stand, bent at the waist, with a water filled cylinder pointed at the floor, there will be slightly less pressure on the glans.

I’ve yet to experience that so far. I’ve used water and walked around doing chores. I haven’t seen any difference.

Water exerts more force: this is exactly what I’m saying does not happen. They exert the same force because of Pascal’s Law and the definition of pressure, but my point is that this is largely irrelevant as more than expansion force is important here.

Air in the system: basically true, but I spoke about how I was talking about systems completely filled with one type of fluid or the other (liquid or gas). I got my pump out the other day and managed to keep the air out completely, or at least visibly, and when I removed the brake bleeder there was no longer air in that system. Anyway, even if there is air, the density of water is still important as expansion force must be transmitted outward through a dense and heavy medium which is pushing down due to gravity and is very incompressible. Also, the amount to which air mitigates the true incompressibility of water depends on how much air you allow into the system as that will dictate the TOTAL compression that can occur in the entire system. So less air = less compression system-wide.

Water pressure/weight: exactly right. Because we are not doing this pumping in a vacuum, gravity comes into play. The weight of Water creates positive pressure just as it does in the deep sea, and this adds compression to the penile tissues. This follows from the high density of water -it is much heavier than air as a result. So this is important, but not the only factor here.